Radiophotolumenescence of Irradiated Polymethylmethacrylate Doped with Some Charge Transfer Complexes

Radiophotolumenescence (RPL) of irradiated and non irradiated thin films of polymethylmethacrylate (PMMA) doped with anthracene (Anth) as a donor, and tetracyanoquinodimethane (TCNQ) as an acceptor, has been investigated. The RPL – glow spectrum was recorded to study the characterizing emission bands from the point of view of glow peak position and intensity and hence the prospective relative sensitivities. RFL – signal fading after one month storage in dark at room temperature post gamma irradiation was also studied. PMMA doped with 6:4 donor to acceptor ratio has been proved to be the most sensitive one with less fading regarding gamma detection. On the other hand 2 Anth: 8 TCNQ was found to be the proper dopant concentration ratio for thermal neutron detection.     

Effect of Gamma Radiation on the IR-Spectra of Polymethylmethacrylate

The IR-spectra of polymethylmethacryate (PMMA) have been measured before and after irradiation in air, in the region of wave number 700–4000 cm^?1. The results showed that the rate of decrease in the absorbance of the IR absorption bands correlated with the type of bond, and the type of vibration whether being stretching, bending or rocking one.

Es wurden die IB-Spektren von Polymethylmethacrylat vor und nach Bestrahlung mit Gammastrahlen in Luft im Wellenzahlbereich von 700 — 4000 cm?1 untersucht. Die Ergebnisse zeifgten, daβ die Geschwindigkeit der Abnahme der IR-Absorptionsbanden mil der Art der Bindung korreliert werden konnten und mit der Art der Schwingung, ob Streck-, Deformations- oder Schaukelschwingung.     

Radiation Dosimetry of some New Dyes Containing 2-Thiohydantoin Nucleus

A number of 5-arylazo-2-thiohydantoins (Ia … e) were prepared. The structure of the prepared materials is established by means of correct analytical data, infrared and electronic absorption spectra. Then the materials were subjected to an absorbed energetic γ-ray dose (5.0 × 10⁷ rd). The infrared and electronic absorption spectra of each material were measured after γ-irradiation. Upon γ-irradiation a considerable change occurs. Furthermore a sequence for the relative stability of the different dyes against γ-irradiation was established.

Eine Anzahl von 5-arylazo-2-thiohydanloine (la … e) wurde synthetisiert und ihre Struktur neben der analytischen Zusammensetzung durch Infrarot- und Elektronenabsorptionsspektren gesichert. Diese Substanzen wurden einer energiereichen γ-Strahlung (5 · 10⁷ rad) unlerworfen und die IR- und UV/VIS-Speklren nach der γ-Bestrahlung wieder aufgenommen. Bei einigen Substanzen wurden bemerkenswerte Veränderungen beobachtet, andere zeigten gegenüber der γ-Strahlung eine relative Stabililät.     

Thermoluminescence induced in Plastics above Room Temperature as a Means of Gamma Ray Dosimetry

The gamma-induced thermoluminescence (TL) in five types of plastics has been studied. The plastics used are Lexan, Makrofol, CA 80-15, LR 115 and CR-39. The result showed that the TL response for Makrofol and Lexan is linear in the range 5 …700 krad, 5 … 3000 krad, respectively. This suggests the possible use of these plastics for gamma dosimetry in the dose range 5 … 3000 krad.

Die gammastrahlen-induzierte Thermolumineszenz wurde an fünf Plastmaterialien untersucht, und zwar an Lexan, Makrofol, CA 80-15, LR 115 und CR-39. Die Ergebnisse zeigten, daβ die Thermolumineszenz-Reaktion für Makrofol und Lexan in Bereich 5 … 700 krad bzw. 5 … 3000 krad war. Das ermöglicht die Verwendung dieser Plastematerialien zur Gamma-Dosimetrie im Dosisbereich von 5 … 3000 krad.     

ESR Induced in CR-39 Plastic as a means of Gamma Ray Dosimetry

The gamma-induced ESR in CR-39 plastic has been studied and the possibility of using it as a gamma-ray dosimeter was investigated. The induced ESR was found to vary linearly with the dose up to 700 krad. The fading of the induced ESR signal at room temperature has been also investigated. The results suggest the possible use of CR-39 plastic for gamma dosimetry in the range 0 … 700 krad.

Es wurde die γ-induzierte ESR-Technik am CR-39 Plast untersucht und ihre Eignung als Gammastrahlen-Dosimeter geprüft. Die induzierte ESR variierte linear bis zu einer Dosis von 700 krad. Das Fading des induzierten ESR-Signals bei Zimmertemperatur wurde ebenfalls untersucht. Die Ergebnisse zeigten, daβ cine Verwendung des CR-39 Plast als Dosimeter für Gammastrahlen im Bereich von 0 … 700 krad möglich ist.     

Effect of Gamma Radiation on the Electrical Resistivity of Some Metal Acetylacetonate Complexes

The effect of gamma radiation on the electrical resistivity of some lanthanide and alkali acetylacetonate complexes was studied for differet doses (20-49 – 36-2 Mr). The activation energy for each complexes was calculated. The obtained results showed that the resistivity as well as the activation energy increase with increasing the radiation dose. An empirical linear relation between the rate of change of resistivity with radiation dose and the ionic radius of the metal was obtained.     

Vector classification, doublet splitting of exciton and biexciton subbands in crystals, and selection rules for transitions between them

The analysis of experimental data on absorption, reflection, luminescence in the region of exciton and biexciton phototransitions in CdS, including P-band structure, shows that there is doubled, contrary to known theory, number of free exciton and biexciton states. This discreapancy is removed in the vector model of these states presented in this paper. The selection rules for transitions between exciton (biexciton) states in crystals taking into consideration their L-T splitting are obtained. The spectra of stimulated FIR radiation on excitonic transitions in CdS, previously obtained experimentally, well fit to these selection rules.     

Use of the momentum approximation in classical scattering calculations

Abstract

The validity range of the momentum approximation in binary collisions : s investigated. It is shown that at high energies, E ? 10 · Z ₁ Z ₂ e ²/a _TF, the approximation is even applicable to scattering angles ? as large as 60 degrees. An empirical formula for the evaluation of the momentum approximation employing the Thomas-Fermi-Moliére potential is given. It reduces the computer time to calculate ? to ～⊥₁₀ of the time consumed in using the standard algebraic functions appearing in the momentum approximation.     

A Refinement of the Hg2F2 Structure by the Use of NMR Data

Abstract

The crystal structure of Hg₂F₂ was studied in works.^1,2 The Hg₂F₂elementary cell of the tetragonal syngony with a=3.66 Å and c=10.89 Å contains two formula units, the space-group being 14/mmm. Hg₂F₂ belongs to those types of structures which possess one non-fixed coordinate (z_F and zHg); hence, the position of the fluorine nuclei may be determined from the value of the second moment of the NMR spectrum of ¹⁹F for powder sample.³ In this case it is ostensibly important, inasmuch as determining the positions of fluorine nuclei near the heavy mercury atoms presents a difficulty for X-ray analysis.     

Further Studies on Gamma Radiolysis of some Di- and Polysaccharides in the Solid State

Extensive measurements have been carried out on cellobiose and cellulose molecules in the solid state comprising infrared and electronic absorption spectra both before and after exposure to an absorbed energetic γ-ray dose (3.0 × 10³ rad). These materials were chosen as representatives of di- and polysaccharides. They have hydrogen bonding of variant origins as they have cyclic structures and the magnitude of γ-radiation damage were evaluated in each case. Gamma radiolytic oxidation mechanism was established for both di- and poly-saccharides investigated.

Es wurden ausgedehnte Messungen an Cellobiose- und Cellulose-Molekülen im festen Zustand ausgeführt, die einer Gammastrahlnng (3,0 · 10³ rad) ausgesetzt waren und von denen vor bzw. nach dieser Bestrahlung Infrarot- und Elektronenabsorptionsspektren aufgenommen wurden. Diese Verbindungen warden als Modellsubstanzen für Di- und Polysaccharide gewählt. Sie besitzen Wasserstoffbrückenbindungen der verschiedensten Art und haben auch cyclische Strukturen. Die Gröβe der Gammastrahlenzerstörung wurde für alle diese Fälle abgeschätzt. Ein Mechanismus der radiolylischen Oxidation wurde für die untersuchtten Di- und Polysaccharide aufgestellt.     

Gamma Irradiation Effects on the Electric Conductivity Behaviour and IR Absorption Spectra of some Haloacetato and Mixed Thiazoles-Haloacetato Transition Metal Complexes

Gamma irradiation effects on the electric conductivity behaviour and IR absorption spectra of some thiazole and haloacetato complexes were investigated. A comparison is made between the rate and activation energies of the thermal annealing of electrical properties of pure and γ-irradiated samples. A mechanism is suggested to explain the observed decrease in the intensity of metal-oxygen bond in the IR spectra of the complexes as a result of γ-irradiation.     

Publicly available database of measurements with the silicon spectrometer Liulin onboard aircraft

Aircrew members are exposed to ionizing radiation due to their work onboard aircraft. ICRP recommended the monitoring of their effective doses because they regularly exceed the limit of 1 mSv per year for the public exposure. The effective doses are routinely calculated by computer codes that take into account flight parameters like altitude, geographic position, and solar activity. This approach was preferred against personal dosimeters method because the effective dose cannot be evaluated experimentally. However, it is generally accepted, that these calculations should be periodically verified by measurements of H*(10) which is frequently used as a surrogate for effective dose. This report refers about the database (available online http://hroch.ujf.cas.cz/∼aircraft/) of long-term measurements with the silicon spectrometer Liulin onboard aircraft. The measurements have been performed since March 2001; so up to date, the database covers a period of 11-years (with a few interruptions) which is usually the duration of the whole solar cycle. The database comprises more than 10⁵ individual records of energy deposition spectra, absorbed dose rates, and ambient dose equivalent rates. Each record contains also the information on all flight parameters needed for calculation of dosimetric quantities by the computer codes, and thus the database represent an useful tool for verification of the routine dosimetry of aircraft crews.     

Radioactivity in Montenegro beach sands and assessment of the corresponding environmental risk

Activity concentrations of the naturally occurring radionuclides ²²⁶Ra, ²³²Th, ⁴⁰K and anthropogenic ¹³⁷Cs in sand samples collected from 20 renowned beaches on the Coast of Montenegro have been determined using an HPGe (high purity Ge spectrometer). The average activity concentrations were found to be 7.4, 5.2, 97.3 and 0.5 Bq kg^?1, respectively. For all sand samples, the radium equivalent activity has been evaluated and found to be lower than the limit of 370 Bq kg^?1. External and internal hazard indices were less than unity. The gonadal dose equivalent was estimated to be on average 75 μSv y^?1, which is about four times lower than the global average for soil (0.3 mSv y^?1). Calculated values of absorbed dose rates showed the range from 3.1 to 28 nGy h^?1, which is below the world median of average values (57 nGy h^?1). The effective dose rate in the range from 3.8 to 34.4 μSv y^?1 was significantly below the recommended limit value for the public (1 mSv y^?1). The highest dose rate was found for the Velika Plaza locality, which also showed heavy metal contents (As, B, Cd, Hg, Cr, Cu, Mn, Ni, Pb, Zn and Ba) significantly higher than in the sand from Jaz, a locality with one of the lowest dose rates.     

低浓度掺杂CdSe/ZnS量子点光纤光致荧光光谱特性研究

制备了一种半导体量子点CdSe/ZnS低浓度掺杂的光纤,测量了不同掺杂浓度和不同光纤长度下光纤出射端的光致荧光光谱,分析了掺杂光纤长度和浓度对量子点光纤荧光光谱特性的影响.结果表明,与掺入光纤前相比,光纤中的量子点荧光发射峰值波长出现红移.在掺杂光纤长度为1~20 cm和掺杂浓度为(0.33~2.5)×10－2mg/mL的实验范围内,红移量随着掺杂光纤长度的增加和掺杂浓度的提高而增大.对给定的激励功率,荧光发射峰值强度对应有一个最佳的量子点光纤长度.对于给定的量子点光纤长度,荧光发射峰值强度对应有一个最佳的量子点掺杂浓度.     

The determination of the x value in doped Hg1-xCdxTe by transmission spectra

Variable-temperature transmission/absorption spectra are measured on As-doped Hg 1 x Cd x Te grown by molecular beam epitaxy.The nonlinear temperature-dependent shift of the absorption edge is also observed,which is similar to our previous report on V Hg (unintentionally)-doped HgCdTe.By referring to the empirical formulas of E g (x,T),the x value of the epilayer is calculated and its inconsistency between the extreme temperatures (e.g.10 and 300 K) is discussed.The results confirm the assumption of the effect of shallow levels on the shift of the absorption edge,and suggest that the x value (or E g) in intrinsic/extrinsic-doped HgCdTe should be determined by referring to as low a temperature as possible (e.g.10 K),and not the commonly used temperatures of 77 or 300 K,when the transmission spectrum should be employed.This can give brief guidelines for fabricating HgCdTe-related devices.     

Possible Link between the Distribution of Atomic Spectral Lines and the Radiation–Matter-Equilibrium in the Early Universe

The uncanny resemblance of the global distribution of all experimentally known atomic spectral lines to the Planckian spectral distribution associated with black body radiation at a temperature of $T\approx 9000\mathrm{K}$ is reported. This value coincides with the critical temperature of equilibrium between the respective densities of radiation and matter in the early universe.     

MCNP simulations of a glass display used in a mobile phone as an accident dosimeter

It has been demonstrated that glass display of mobile phones can be used as a device for accident dosimetry. Published studies concentrated on the experimental investigation of parts of the glass display. In the work presented here, the experimental results are compared with results of radiation transport calculations using the Monte Carlo code MCNP5.An experimental setup of an irradiation of an extracted glass display is simulated. The simulation is then extended to a simulation of a modern day mobile phone consisting of all major parts. Simulations are performed for various irradiation conditions and different geometric and material properties.The results of the simulation show a good agreement with the experiments for an extracted glass sample as well as for an actual modern mobile phone. The glass display is exposed to radiation in various angular and energy distributions. Simulated results were compared to experimentally determined results. The effects of the irradiation condition on the photon energy dependence were investigated and variations in the material constants of the display glass composition were discussed. This work affirms the usability of a mobile phone as a versatile and flexible accident radiation detector.     

Estimation of hydroxyl free radicals produced by ultrasound in Fricke solution used as a chemical dosimeter

Hydroxyl free radicals produced in Fricke solution exposed to 80 kV X-rays or 23 kHz ultrasound (intensity 3 W cm⁻²) or 20 kHz ultrasound (intensity 18.9 W cm⁻²) or 3.5 MHz clinical ultrasound (intensity 1.47 W cm⁻²), as estimated from the Fricke dosimetric data, exhibited a linear dose-response relationship. The dosimeter was found to be effective in the concentration range 1.0–8.0 mM of FeSO₄ solution. The hydroxyl radicals produced in Fricke solution were inhibited by the OH radical scavengers dimethyl sulfoxide (200 mM), -histidine (10 mM) and sodium benzoate (10 mM) in a manner proportional to the rate constants of their reaction with the OH radicals. The power threshold for OH radical formation, which is presumably the threshold for cavity formation, was estimated for 23 kHz ultrasound by this dosimeter as 1.28 W cm⁻² for a 4 cm³ sample volume.     

Effect of Gamma Radiation on the IR Spectra of Some Divalent and Trivalent 8-Hydroxyquinoline Complexes

The I R spectra of ten elements chelated with 8-hydroxyquinoline were measured before and after gamma irradiation with different doses (7–518 Mrd) and discussed. It was found that the rate of decrease, K, of the absorbancy of M—O and (C—O)-M stretching vibration bands depends on the chelated cation. Moreover, the Cu 8-hydroxyquinoline complex is suggested as gamma dosimeter for doses ranging from 4.8 to 160 Mrd.     

Broadening of the Hg 2537-Å line as a function of the density of Hg atoms in the presence of several metals

Conclusions The change in the nature of line broadening of the Hg 2537-Å line depends both on the density of metallic atoms and on the density of mercury atoms. It follows from this that for the systems Hg+Cd, Hg+Zn, and Hg+Mg the absorbing centers are weakly bound complexes of the type Hg+metal.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 130–131, February, 1975.